diff --git a/weboob/backends/cragr/pages/login.py b/weboob/backends/cragr/pages/login.py
index 102806ad..e8f8302c 100644
--- a/weboob/backends/cragr/pages/login.py
+++ b/weboob/backends/cragr/pages/login.py
@@ -16,7 +16,10 @@
 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 
 
-import ClientForm
+try:
+    from mechanize import ControlNotFoundError
+except ImportError:
+    from ClientForm import ControlNotFoundError
 
 from .base import CragrBasePage
 
@@ -33,7 +36,7 @@ class LoginPage(CragrBasePage):
         try:
             self.browser['numero'] = login
             self.browser['code'] = password
-        except ClientForm.ControlNotFoundError:
+        except ControlNotFoundError:
             try:
                 self.browser['userLogin'] = login
                 self.browser['userPassword'] = password
diff --git a/weboob/backends/youporn/pages/base.py b/weboob/backends/youporn/pages/base.py
index 3b6ca9ce..5a4b4a86 100644
--- a/weboob/backends/youporn/pages/base.py
+++ b/weboob/backends/youporn/pages/base.py
@@ -15,8 +15,11 @@
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 
+try:
+    from mechanize import ControlNotFoundError
+except ImportError:
+    from ClientForm import ControlNotFoundError
 
-import ClientForm
 from mechanize import FormNotFoundError
 from weboob.tools.browser import BasePage
 
@@ -30,5 +33,5 @@ class PornPage(BasePage):
             self.browser.select_form(nr=0)
             self.browser.submit(name='user_choice')
             return False
-        except (ClientForm.ControlNotFoundError,FormNotFoundError):
+        except (ControlNotFoundError,FormNotFoundError):
             return True
diff --git a/weboob/tools/browser/browser.py b/weboob/tools/browser/browser.py
index 2c44b43b..b988b719 100644
--- a/weboob/tools/browser/browser.py
+++ b/weboob/tools/browser/browser.py
@@ -19,7 +19,10 @@
 import mechanize
 import urllib
 import urllib2
-import ClientForm
+try:
+    from mechanize import ControlNotFoundError
+except ImportError:
+    from ClientForm import ControlNotFoundError
 import re
 import time
 from logging import warning, debug
@@ -174,6 +177,7 @@ class BaseBrowser(mechanize.Browser):
         if self.password:
             try:
                 self.home()
+            # Do not abort the build of browser when the website is down.
             except BrowserUnavailable:
                 pass
 
@@ -367,5 +371,5 @@ class BaseBrowser(mechanize.Browser):
                     else:
                         value = self.str(args[label])
                 self[field] = value
-        except ClientForm.ControlNotFoundError:
+        except ControlNotFoundError:
             return